1. Field of Use
This invention relates to electric battery powered detachably connectable drive units for wheelchairs.
2. Description of the Prior Art
Various types of battery powered drive units for wheelchairs are known or in use and U.S. Pat. Nos. 3,921,744; 3,912,032; and 3,939,931 illustrate the state of the art of detachable drive units. The following U.S. patents disclose detachable drive units adapted for propulsion of equipment other than wheelchairs, such as trailers and golf carts: Nos. 4,210,217; 4,037,678; 4,105,084; 4,019,597.
Some prior art detachable drive units are relatively complex and costly to manufacture and are difficult or impossible to attach to a wheelchair unless the latter has been specially constructed or modified to accept the detachable unit. Furthermore, some units when in place prevent or interfere with easy user ingress to or egress from the chair. Also, some units cannot be easily operated or controlled by anyone, such as an attendant, except an occupant of the wheelchair, thus making it difficult to move the chair while the unit is attached.